O2131: A Prospective Cohort Study of Serum Intestinal Fatty Acid Binding Protein (I-FABP) as a Predictor of Necrotizing Enterocolitis (NEC).

Background: Necrotizing enterocolitis is a devastating condition that commonly affects preterm infants. Early and accurate recognition of preterm neonates developing NEC will be useful to prevent progression of the disease and to test the efficacy of therapeutic interventions. We have previously reported the potential of intestinal fatty acid binding protein (I-FABP) as a biomarker to identify NEC prior to clinical diagnosis in retrospective studies. This is an interim analysis of a prospective clinical observational study aimed at identifying biomarkers for early diagnosis of NEC.
The purpose of this analysis was to determine whether serum I-FABP measured at advancement of enteral feeds could herald the onset of NEC prior to clinical suspicion.

Methods: Preterm neonates < 32 weeks gestation and < 1500 grams were enrolled within the first three days of life and monitored with continuous abdominal near-infrared spectroscopy (NIRS) for 5 weeks or until abdominal surgery. Blood was obtained for biomarker assessment at enrollment, feed initiation, and 6 hours following every 20 ml/kg/day feed advancement. Blood collections were stopped at 120 ml/kg/day of feeds or development of NEC, whichever occurred first. Clinical information was obtained on all patients until NICU discharge or 6 months of age. ELISA was used to assay serum I-FABP in patients who developed NEC and their weight and age-matched controls. Data were analyzed using paired t-tests and repeated measures ANOVA with mixed-effects analysis.

Results: From June 2021 to March 2024, 96 patients were enrolled but 6 withdrew from the study. Of the remaining 90, 12 (13.3%) were diagnosed with NEC. Only 5 of the NEC patients were diagnosed during the period of sample collection - within a median of 1 [1-21] day after the final sample collection. Serum I-FABP (sI-FABP) values remained at low levels in healthy controls and also NEC patients at the initial stages of feeding however, in patients who developed NEC, sI-FABP trended upwards with increasing enteral feed volume (Figure 1).There was a significant increase in serum I-FABP at the final sample, obtained prior to the clinical suspicion of NEC, when compared to the patients’ own earlier samples (p < 0.01) or age/weight-matched controls (p < 0.01) (Figure 2a). By receiver operating characteristic (ROC) curve analysis identified sI-FABP of 4.2 ng/ml to be predictive of NEC with 80% sensitivity and 100% specificity (AUC 0.9; p=0.05) (Figure 2b).

Conclusion: Elevation in serum I-FABP with increase in enteral feeding correlates with, and precedes, clinical suspicion of NEC. In addition, the temporal relationship of NEC and the advancement of feeds may suggest a role for increased metabolic demands on the gut predisposing to the development of NEC. This prospective study endorses the utility of serum I-FABP as a biomarker for early diagnosis of NEC.